The present invention relates to a vertically slidable window comprising two upper and lower sashes to open and close the window opening and is intended to provide a vertically slidable window whose opening and closing operation is easy and smooth and which enables the effective ventilation of the room.
Conventional windows of this vertically slidable type have been constructed such that the upper and lower sashes are tied to each other by a rope which is entrained around a pulley supported on a shaft on the upper end of the outer window frame so that the two sashes can be raised and lowered in interlocked relation. With this construction, however, if the rope breaks during use, the two sashes being raised or lowered suddenly fall and nip the user's hands, thus forming a cause of injury to him. Further, the rope tends to come off the pulley when twisted or vibrated, making it impossible to raise or lower the sashes, and prolonged use of the rope causes the elongation of the rope, making it impossible to raise or lower the sashes to the extreme limits, thus causing troubles to the opening and closing of the window.
Accordingly, an object of the invention is to provide a vertically slidable window which involves no danger of the sashes accidentally falling during the raising or lowering thereof, thus preventing injury to the user.
Another object of the invention is to provide a vertically slidable window which, even if given shocks or vibrations, will not cause troubles to the raising and lowering of the sashes, so that it can be used in a stabilized manner.
A further object of the invention is to provide a vertically slidable window wherein the upper and lower sashes, even if used for a long time, can be raised and lowered to the extreme limits, ensuring positive opening and closing of the window.